1. Field of the Invention
The invention relates to a coffee maker, more particularly to a programmable coffee maker that is capable of automatically canceling a preset brewing time.
2. Description of the Related Art
In a conventional coffee maker, an electric heating device is mounted in a base, and is controlled by a control circuit to heat a supply pipe. Water in a water reservoir is heated as it passes through the supply pipe, and drips into a filter basket that contains ground coffee. Brewed coffee from the filter basket is collected in a flask on the base. The control circuit of some conventional coffee makers can be programmed for brewing coffee automatically at a preset time of day. However, the conventional coffee makers are unsafe since, unless the preset brewing time was cancelled, the conventional coffee makers will be activated automatically even when the water reservoir is empty.
Therefore, the object of the present invention is to provide a programmable coffee maker that is capable of automatically canceling a preset brewing time to overcome the aforesaid drawback of the prior art.
According to this invention, a programmable coffee maker comprises a water reservoir for receiving water therein, a base disposed at a lower end of the water reservoir, a filter basket, and a control circuit mounted on the base. The base includes a housing, an electric heating device mounted in the housing, and a supply pipe in fluid communication with the water reservoir and heated by the electric heating device when electric power is supplied to the electric heating device. The filter basket is disposed above the base and is disposed to receive heated water from the supply pipe. The control circuit includes an input unit operable so as to input a preset brewing time, a heater controller connected to the electric heating device and operable so as to control electrical connection between the electric heating device and a power supply, a sensor unit for providing a cancel signal when temperature at the supply pipe reaches a predetermined critical temperature indicative of a condition where the supply pipe is heated with the water reservoir being in an emptied state, and a processor connected to the input unit, the heater controller, and the sensor unit. The processor has an internal clock with a current time output, and controls the heater controller to make electrical connection between the electric heating device and the power supply when the preset brewing time coincides with the current time output. The processor cancels the preset brewing time, and controls the heater controller to break the electrical connection between the electric heating device and the power supply after the processor receives the cancel signal from the sensor unit.